Tools that are free — Works with Firefox

6 match your filters — 4 of them answered our check today.

Watching this group for 20 days · how we check

This week3 new arrivals

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HAR File Viewer

Live

A free HAR file viewer that runs entirely client-side (nothing uploaded) and lets you inspect requests, headers and timing waterfalls — a real developer debugging tool.

FreeData stays with you

What to know▼

How it works: Opens HAR exports from Chrome, Firefox, Safari, or Edge and lets you inspect requests, headers, cookies, request/response bodies, query params, and a timing waterfall, with filtering by status, method, type, or URL and redaction of sensitive headers.
What's different: Runs 100% client-side, so no captured network data leaves your browser.
Pricing: Free.
Best for: Developers debugging network requests and performance.

Watched for 14 days · last checked today

Highlite

Live

A free browser extension that lets you highlight, annotate, and sticky-note any webpage without creating an account, for research or design feedback.

Domain registered 15 months ago

FreeNo sign-up

What to know▼

How it works: Highlight text, add sticky notes, draw, and add arrows to annotate and share any webpage.
Pricing: Free Chrome and Firefox extension, no account needed.
Best for: Deep research or design feedback.

Watched for 8 days · last checked 2d ago

Dailo: Tabs and Bookmarks

A bookmarks and tabs manager built for productivity

FreeWorks offline

What to know▼

How it works: Açık sekmeleri Spaces'e dönüştürür, linkleri erteler, tek kısayolla odaklanır; kaydedilen link/görev/notların göründüğü özelleştirilebilir yeni sekme sayfası sunar.

First seen today

Bezel

Frames your web page inside a real iPhone, Pixel, Galaxy or iPad simulation in your browser — true viewport, pixel density and touch signals, running 100% locally so localhost and logged-in pages just work.

Free

What to know▼

How it works: Runs entirely in-browser against 93 verified device profiles; includes screenshots, recording, side-by-side compare and environment spoofing.
Pricing: Free on Chrome, Edge and Firefox.
Best for: Developers and QA testing responsive design without physical devices.

First seen today

Mobile Simulator MSIM

Live

Free side-by-side multi-device website preview tool for Chrome and Firefox with synced scrolling.

FreeNo sign-up

What to know▼

How it works: Opens phones and tablets side by side in Chrome and Firefox with synced scroll and rotation to catch responsive bugs.
Pricing: Free core, no account required.
Best for: Web developers testing responsive designs.

Watched for 3 days · last checked 1d ago

8Dfy

Live

A free browser extension that turns YouTube audio into immersive 8D spatial sound.

Domain registered 3 months ago

FreeCan export my data

What to know▼

How it works: Transforms YouTube audio into immersive 8D spatial sound with multi-band surround, HRTF 3D positioning, and binaural beats, with shareable clips and lossless export.
Pricing: Free.
Watch out: Chrome and Firefox extension; no downloads or DAWs needed.

Watched for 8 days · last checked 6d ago